Complex artificial filaments



J 9 19 2 HANS-JOACHIM DIETZSCH ETAL 3,015,873

COMPLEX ARTIFICIAL FILAMENTS Filed March 8, 1956 Hans -J acluvufihzfzscl Otto Dlgtzz Byd? 4273 llnited States Patent G 3,015,873COMPLEX ARTIFICIAL FILAMENTS Hans-Joachim Dietzsch, Horn, and OttoDietzsch,

Wangen, Germany, assignors to Trikotfabriken .l. Schiesser A.G.,Radolfzell (Bodensee), Germany Filed Mar. 8, 1956, Ser. No. 579,249Claims priority, application Germany Mar. 8, 1955 1 Claim. (Cl. 28-82)This invention relates to complex artificial filaments comprising two ormore longitudinal sections of different spinning materials. Suchfilaments may comprise a hollow gas filled core or may consist ofcompound structures of two or more different spinnable materials joinedin centrally symmetrical or non-symmetrical distribution.

An object of the invention resides in the fact that artificial filamentsof monotonic cross-sectional composition have rather primitive qualitiesin use even if made of modern highly adaptable materials of polymericmolecular structure. Contrary thereto the highly adaptable naturalfilaments have a structural composition of a plurality of single layerswhich aid each other in an overall improvement of the finishedfilaments.

It is a primary object of this invention to provide artificial filamentsof non-homogenous material as to cross-section of which the differentmaterials also are heterogeneously distributed across the longitudinalsection of the filament in substantially periodic repetition. Thesefilaments differ from known so-called foam filaments by their regularstructure both in cross and longitudinal sections and their imperforatedsheath.

The production of these said artificial filaments is based on the use ofmulti-orifice spinnerets whereby the different materials of equal ordifferent state of aggregations are joined in a geometricalconfiguration formed exactly during the spinning process. Suchmulti-orifice spinnerets are the subject matter of a co-pendingapplication, Serial No. 570,401, filed March 8, 1956.

The heterogeneous distribution of the different filament materials in alongitudinal section may consist in a periodically repeating change ofthe ratio in the quantity of the different materials as to thecross-section of the compound filament.

The term filament denotes only a short term for filaments of all shapesand cross-sections, namely, round filaments as well as fiat orribbon-like structures. The spinning materials comprise all substancesadapted to be shaped in solid, dissolved or molten state. The termspinning denotes only a short word for the all-embracing principle ofthe plastic working of materials under pressure or tension, in additionto spinning in the narrow technical sense, and it comprises also theextrusion pressing or drawing, of injection molding or pressure casting,etc.

This invention primarily has to do with materials of organiccomposition, as cellulose, cellulose compounds, aldehyde condensationproducts, albumin and other substances containing nitrogen-like casein,gelatine, and especially artificial resins comprising vinyl, acryl,styryl and other non-saturated groups, especially modern linearpolymers. According to their natures, these spinning materials areshaped into various fibrous structures by loss of heat or drying out orby suitable solidifying agents as liquid precipitants, cooling gas, etc.

According to the demands on the mechanical and bygienic qualities ofsuch filaments such as mechanical strength, heat insulating properties,humidity, or sweat storing properties, etc., the spinning materials aredistributed among the inner or outer layers. In the following, someexamples of artificial filaments made of two or more materials arelisted:

Filaments made of two materials Nitrogenous component.

Foamy polyamide. Viscose Foamy viscose (by foam-generating components)Do Dull lustre viscose.

Filaments made of three materials (1) Sheath (2) Outer core (3) Innercore material material material Polyamide.. Formalized p01yamideNitrogenous compound. Do d0 Foamy polyamide. Do Weakly acetylized cel-Do.

lulose and water-storing softener. Acetylcellulosedo Foamyacetyl-cellulose.

Filaments made of four materials (1) Sheath material (2) Outer core (3)Intermediate (4) Inner core teners.

A preferred object of this invention consists of structures in the shapeof so-called cellular filaments comprising a tube-like and imperforatedsheath and partitions sub-dividing the hollow interior to form cells. Asdemonstrated by grasses, crop-grasses, etc., fibrous or rodlikestructures of this type have an extremely high tensile strength andlateral stiffness and therefore are useful for many technical purposes.By microscopic examination it has been found that the cellular cavitiesfilled with air or gas are able to take on external humidity by osmoticprocesses in the sheath. If the cavities are filled with awater-storing, e.g. swellable substance, rather considerable quantitiesof moisture can be absorbed by the filament. Thus, for the first timethereis a possibility of producing textile filaments made of hydrophobicmaterial like polyesters or polyamides comparable with cotton withregard to humidity and sweat adsorption. Furthermore, the gas content ofthe cells guarantees a very high heat insulating factor like that ofnatural filaments.

It is a further object of this invention to produce partitions ofwater-adsorbent material, e.g. formalized polyamide.

It is a further object of this invention to provide artis ficialfilaments, the cavities of which are filled with pharmaceuticalsubstances producing therapeutical or hygienic effects. Such impregnatedfilaments are useful for making clothing or for surgical treatment.

It is a further object of this invention to produce artificialfilaments, the cavities of which are filled with a fatty substance whichis unable to diffuse through the outer layer. Such filaments areeffective against undesired absorption of moisture, bodily fat, etc.

It is a further object of this invention to produce artificialfilaments, the cavitiesof which have been made incompressible by fillingthem with microporous solid substances, as aluminum hydroxide,silicagel, etc.

It is another object of this invention to produce cellular filamentsprovided with axially oblong partitions so that the cavities areseparated from one another for a certain distance. Such filaments areshaped like a bubble chain and may be used instead of bedfeathers, aslining or upholstery material and generally everywhere where elastic andheat-insulating multi-layer fibrous structure is needed.

It is a further object of this invention to produce artificial filamentsprovided with cellular cavities loosely filled by a solid substance.Such filaments are useful for technical as well as aesthetic purposes.

It is a further object of this invention to produce artificial filamentshaving a rough or bristly outer surface. Fliaments of this type have nolustre and therefore appear like natural filaments. If the appendagesare long enough, the heat insulating property, the felt-ability andother textile qualities are improved.

It is another object of this invention to produce artificial filamentscomprising dyes or pigment embedded in the cellular cavities. Suchfilaments will produce special optical eifects. These dyes or pigmentsmay be fluorescent or phosphorescent.

It is a further object of this invention to produce artificial filamentsprovided with reflecting inner surfaces by applying a reflecting silverlayer by methods known in the mirror art.

It is another object of this invention to produce artificial filamentsprovided with light-sensitive inner surfaces. The light sensitivesubstance may consist of a diazo compound sensitive to the short wavepart of the spectrum. Light sensitive filaments of this type need not bestored in a dark room like those made of light sensitive silver salts.Fabrics or webs made of such filaments may be ornamented by merephotographic processes. Furthermore, these diazo compounds may be usedas dyestuif coupling components for producing colored patterns withoutprinting screens, etc.

This invention is not restricted to simple cellular filaments but mayalso be used for improving artificial filaments comprising a pluralityof axially extending chains of cells distributed in cross-section.

This invention also deals with filament bundles comprising a pluralityof single filaments shaped according to this invention. Therefore, it isa further object of this invention to produce a filament structurecomprising at least two substantially parallel filaments interconnectedby material bridges in regular intervals and not by textile ligatures asis normally the case.

These filament structures may have predetermined cavity volumes andbristly surfaces or both and can be produced in large sizes byappropriate spinning apparatus.

Furthermore, this invention deals with the methods of producingfilaments and filament structures of the beforementioned kinds.Therefore, another main object of this invention relates to a method ofproducing complex artificial filaments comprising the steps of feedingthe spinning material forming the filament sheath, to the ring nozzle ofa spinneret comprising at least two nozzle stages and the spinningmaterial forming the filament core to the nozzle inside the ring nozzleof said spinneret and acting on said core material when still in plasticcondition to periodically change its cross-sectional content along thelongitudinal axis of the forming complex filament and to set saidcomplex filament. If the core material has a foamy structure it ispreferred to cause the fine foam bubbles to unite in a minority oflarger bubbles filling the hollow cross-section of the filament.

The foamy material can be produced in different ways. The dispersion maybe performed by mechanical means, especially by ultra-sound and in thestorage vessel or during the passage of the material up to the spinneretnozzle. It is also possible to generate the foamy core material by apulsating mixing of the core material and gas at the nozzle outletserving to transfer the vibrations.

The foamy material also can be produced by chemical reactionsdecomposing the primary core material. This material may produce gaseousreaction products. The internal decomposition may be due to unstablechemical structure or possibly may be caused by thermal influence.

The foamy structure also can be produced by saturating the core materialwith compressed gas and releasing the pressure at the nozzle outlet toliberate the excess of gas as a form of fine bubbles as in the case ofopening a bottle of champagne.

There are also several methods of changing the original fine foam intocoarser bubbles. A preferred principle of operation consists intemporarily reducing the viscosity of the material and using the surfacetension forces activated thereby to reduce the free surface of thebubbles as in the case of a soap bubble. Actually the low-viscousmaterial separates from the gas and contracts to form surfaces ofminimum surface energy. In the present case there are built uppartitions of hyperbolic shape bridging the core space of the tubularfilament at intervals. In an embodiment of this method a solvent isintroduced into the foamy core of the filament of which the sheath hasbecome solidified, for reducing the viscosity of the core material andagain removed by thermal influence when the bubbles have become coarse.The dried out core material will thus form the partitions. In many casesthe surface tension forces will become eificient by mere heating of thefoamy core material inside the tubular filament. The heating may be doneinductively by adding substances of high electric A.C. resistance or lowspecific heat.

Experiments have shown that during production of the filaments accordingto the invention the surface tension forces of the sheath material mayconstrict the hollow tubular filament and keep off the core material.For avoiding this inconvenience the surface tension of the sheathmaterial has to be kept low. This may be done by an appropriate gaseousphase surrounding the filament structure leaving the nozzle orifice, orby reducing the viscosity of the sheath material by cooling. It is alsouseful to avoid or at least to reduce the so-called stretch spinningeffect. For this reason, the sheath material may be fed through a narrownozzle in quantities corresponding with the desired width of the finalsheath. Another principle of operation consists in leaving unchanged thesurface tension forces of the sheath material and reduce the formationof the foamy core material by enlarging the resistance of passage alongthe inner nozzle by reducing the cross-section of the nozzle and/or byraising the viscosity of the foamy core material.

Artificial filaments provided with a rough and especially bristly outersurface may be produced in several ways.

According to one embodiment of this part of the invention a three stagespinneret is used and the outer ring nozzle is fed with a foamy materialgenerating an additional layer of rather coarse bubbles on the sheath ofthe tubular filament produced by the two inner nozzle orifices in thepreviously described manner. These outer foam bubbles are then caused toburst open into splinters forming the desired appendages of the sheathof the tubular filament. It will be noted that these superficial foambubbles are not connected to the core by passages across the sheath asin the case of the known filaments of foamy consistency throughout thewhole material.

According to another embodiment of this part of the invention, anadditional layer of non-stretchable material is generated on the sheathof the tubular filament and subdivided by adhering warty splinters bystretching the solidified tubular filament this stretching is notfollowed by the non-stretchable material and is thereby torn into smallpieces.

A third possibility of producing cellular filaments provided with ratherlong and bristly appendages consists in connecting a plurality offilaments simultaneously spun in clusters by local material bridgesformed mechanically, that is, by vibrating nozzles or by ultrasonicvibrations generated in the viscous material and thereafter tearing offthese bridges by an additional procedure. Spinning under the influenceof ultrasonic vibrations will also cause an uneven surface of thefilament.

Furthermore, according to still another embodiment of the invention, anirregular end and especially bristly outer surface of the tubularfilament may be produced by making the sheath out of a material filledwith magnetic particles and subjecting it, when still viscous, to theinfluence of an annular magnetic field, pulling out of the outer surfaceof the filament the magnetic particles and parts of the sheath materialadhering to each particle. The magnetic particles later may be removedby shearing or by chemical solvents. By proper adjustment of theviscosity of the sheath material rather long fibers can be pulled out toproduce filaments of wool-like appearance and qualities.

The magnetic particles may also be left in the bristly filaments to beused as electroinductive heat generators. Filaments of this kind areuseful for medical purposes.

By the just-described method of connecting filaments by local materialbridges filament structures of cushion or mat-like appearance may beproduced.

Structures in the form of bladder chains may be produced by using thesurface tension forces previously mentioned. Accordingly, the sheathmaterial may be spun in a state of low viscosity eventually caused byperiodic elevations of the temperature in or outside the nozzle orifice.

It is also possible to pulsatingly feed the eventually gaseous corematerial which periodically will expand the low viscous sheath materialinto a bubble chain. The feed of the core material may be controlled bymembrane controlled valves.

This invention also deals with the production of small dimensionedfilament structures in bubble form. An embodiment of this inventionconsists in producing a hubble chain in the previously described manner,subdividing it into separate bubbles by interrupting the connectingsections, causing the bubble sections to freely pass a gaseous or fluidmedium, reducing the viscosity of the filament material to form bubblesof equal wall thickness due to the surface tension forces set free andfinally solidifying these bubbles before being collected. This methodimitates the production of soap bubbles on a manufacturing scale. Thevolume of the bubbles may be increased by introducing gas generatingsubstances into the cavity of the bubble. The specific weight of suchartificial bubbles depends on the bubble size and is always very low.The bubbles are also compressible and are therefore very useful for lifejackets and sound and/or heat insulating structures. For improving thecapacity of resistance against mechanical and/or thermal stresses thebubbles may be left incompletely filled. Such untight bubbles may beproduced by enlarging the bubble volume when its sheath is in theplastic state, solidifying the sheath material in its expanded state andto again normalize the conditions which caused the volume enlargement.

An embodiment of this part of the invention consists in subjecting thebubble to a subnormal outer pressure, temporarily reducing the viscosityof the sheath material e.g. by heat to permit the bubble to expand andbecome solidified in this expanded state and finally restoring thenormal outer pressure.

Another embodiment of this invention consists in introducing a fluid ofcomparably low vapour pressure into the cavity of the bubble e.g. byosmotic diffusion across the sheath, elevating the inner pressure of thebubble by temporarily vaporizing said fluid, permitting the bubble toexpand and solidify in the previously described manner, reducing theinner pressure by cooling and finally removing the expansionfluid.

The before described bubble chains may be formed into fleece or matlikestructures by arranging a plurality of such bubble chains inside-by-side and superposed positions and materially uniting them at thepoints of contacts, e.g. by temporary infrared heating. Such structuresare highly elastic and heat insulating. Instead of 6 bubble chains aplurality of single bubbles may be united in the same way.

A further principal subject matter of this invention consists in amethod of producing complex artificial filaments of the described typescomprising the steps of primarily combining the different materials toform an elongated structure in the shape of a rod or wire having thefinal complex sectional structure and to change this raw stock intocomplex filaments of the desired number by known methods of the Wiredrawing technics. The advantage of this method consists in thepossibility of using larger installations and especially nozzles oflarger diameter for the production of the complex raw stock and normaland simple dies for drawing the raw stock into filaments of the desiredfinal number.

The annexed drawing illustrates various embodiments of the invention inwhich,

FIGURE 1 is a longitudinal section of a form of filament with filledcore,

FIGURE 2 is a longitudinal section of a modified filament showingappendices thereon,

FIGURE 3 is a longitudinal section showing a cellular thread in a stateof production,

FIGURE 4 is a longitudinal section showing the cellular thread of FIGURE3 in another stage of production,

FIGURE 5 is a diagrammatic side view of another embodiment of theinvention.

FIGURE 6 is a longitudinal section of a further modified filament, and

FIGURE 7 is a longitudinal section of another modified filament.

In FIGURES 1 to 4, reference numeral 1 designates the material formingthe tube sheath of constant size. In the embodiments according toFIGURES 1, 3 and 4 the foamy material 2 is positioned inside the sheath1, and in the embodiment according to FIGURE 2, the foamy material 2 ispositioned outside said sheath 1.

FIGURE 1 diagrammatically shows the special embodiment of the inventionwhereby the cells formed by the core material 2 are filled with a loosefiller 3 made of different material.

In the embodiment shown in FIGURE 2 the thread component 2 forms bristlyappendices on the outer surface of the tube sheath 1.

FIGURES 3 and 4 diagrammatically show two stages of a cellular thread.FIGURE 3 shows the thread in an intermediate state of production, theinterior of the tube sheath 1 still being filled with irregularly shapedbubbles made of the primarily foamy core material 2". This foam is againliquified by a solvent diffusing through the tube sheath 1 in thedirection of the arrows of FIG- URE 3 thereby changing into a muchsmaller number of much larger cells separated by walls perpendicular tothe thread axis due to surface tension effect taking place in theliquified mass 2, when finally the solvent is again removed from theinner space of the hollow thread in the direction of the arrows ofFIGURE 4.

FIGURE 5 shows a so-called bubble chain consisting of thin-Walledgas-filled, and substantially spheroid hollow chambers 4 and short,thread-like bridges 5 having a full or hollow cross-section and unitingthe hollow chambers 4.

FIGURE 6 shows a filament having three layers of which 11 is the outersheath as polyamide, 12 is the inner sheath as formalized polyamide and13 is the core as a series of cells of polyamide.

FIGURE 7 shows a filament of which 21' is the outer sheath and iscomposed of acetylcellulose. The intermediate sheath 22' is a polyamideand theinner sheath 23 is a formalized polyamide. The core 24' iscomposed of a series of cells consisting and made of a polyamide.

We claim as our invention:

An extruded filament consisting of a sheath and a core composed ofdifferent materials and united with one another by intermixture at thecontact area of the different materials, the core consisting of asequence of cells each shaped against the inner surface of the sheathand separated from each other 'by partitions extending in spacedrelation each with its central cross sectional plane at right angles tothe longitudinal axis of the filament and each partition being shaped bysurface tension.

2,222,797 Dreyfus Nov. 26, 1940 8 Sisson et al Sept. 30, Hall et a1.July 19, Hall et a1 Dec. 27, Ladisch Oct. 16, Ladisch Oct. 7, WiczerDec. 2,

FOREIGN PATENTS Great Britain Nov. 14, Great Britain May 23, France Nov.17,

